1905/1906 Calibration Reference Chart / Primary Metering
Model 1905/1906 Rod/Jet Reference Chart
This document provides a reference chart for calibrating Edelbrock 1905 and 1906 carburetors, detailing primary metering adjustments.
Calibration Chart Description
The primary metering calibration chart is a grid that plots Power Mode (ranging from Lean to Rich) on the horizontal axis against Cruise Mode (ranging from Lean to Rich) on the vertical axis. The chart is divided into numbered zones, representing different calibration stages. The axes are labeled with stages such as "3 stages Lean (12%)", "2 stages Lean (8%)", "1 stage Lean (4%)", "Base Power Mode", "1 stage Rich (4%)", "2 stages Rich (8%)", and "3 stages Rich (12%)". The chart indicates that numbers in black represent steps obtainable using a specific Calibration Kit (TBD) plus stock jets and metering rods, while numbers in white represent steps obtainable using jet and rod combinations shown on a subsequent page.
Primary Metering Reference Table
The following table lists specific calibration settings:
| REF # | MAIN JET | METERING ROD | CHANGE FROM BASE |
|---|---|---|---|
| 1 | 1429 (.101) | 1449 (.070 x .037) | none - stock calibration |
| 2 | 1427 (.098) | 1449 (.070 x .037) | Jet |
| 3 | 1430 (.104) | 1449 (.070 x .037) | Jet |
| 4 | 1429 (.101) | 1416 (.065 x .042) | Rod |
| 5 | 1429 (.101) | 1445 (.065 x .047) | Rod |
| 6 | 1429 (.101) | 1446 (.070 x .042) | Rod |
| 7 | 1429 (.101) | 1447 (.068 x .047) | Rod |
| 8 | 1429 (.101) | 1455 (.073 x .042) | Rod |
| 9 | 1429 (.101) | 1456 (.073 x .047) | Rod |
| 10 | 1430 (.104) | 1454 (.073 x .037) | Rod & Jet |
| 11 | 1431 (.107) | 1419 (.075 x .042) | Rod & Jet |
| 12 | 1431 (.107) | 1459 (.075 x .047) | Rod & Jet |
| 13 | 1427 (.098) | 1446 (.068 x .042) | Rod & Jet |
| 14 | 1427 (.098) | 1442 (.063 x .037) | Rod & Jet |
| 15 | 1427 (.098) | 1446 (.070 x .042) | Rod & Jet |
| 16 | 1426 (.095) | 1442 (.063 x .037) | Rod & Jet |
| 17 | 1426 (.095) | 1444 (.065 x .037) | Rod & Jet |
Secondary Metering
The factory calibration jet is shown in the center column. For leaner or richer calibration, use the jet # indicated in the appropriate column.
The secondary metering chart displays jet sizes for different stages:
- 3 Stages Lean (12%): JET #1424 (.089)
- 2 Stages Lean (8%): JET #1425 (.092)
- 1 Stage Lean (4%): JET #1426 (.095)
- SECONDARY Stock Calibration: JET #1427 (.098)
- 1 Stage Rich (4%): JET #1429 (.101)
- 2 Stages Rich (8%): JET #1430 (.104)
- 3 Stages Rich (12%): JET #1431 (.107)
Jet Identification
All Edelbrock jets have a "120-" prefix. The last three digits minus 300 indicate the actual jet size. For example:
- 120-398 = .098" jet (Edelbrock part number 1427).
- 120-401 = .101" jet (Edelbrock part number 1429).
Calibration Procedure
- Step 1: Select the combination of Cruise Mode and Power Mode fuel-metering stages desired for your calibration. Normal calibration changes should be within the gridded diagonal area, meaning Cruise and Power mode changes should be in the same direction (either richer or leaner) and generally by the same amount.
- Step 2: Find the number that is nearest your desired combination. This is your Calibration Reference Number.
- Step 3: Proceed to the next page (not included in this document) to find the Calibration Reference Number selected in Step 2. This will list the Main Jet and Metering Rod required to achieve the desired fuel metering for the primaries.
